1. Field of the Invention
The present invention relates to a roller adapted to convey a metal mould of an injection moulding machine and the like in the horizontal direction.
2. Description of the Prior Art
Among such conveying rollers, conventionally there are ones disclosed in Japanese Utility Model Publication No. 59-140821. This conventional conveying roller is constructed as follows as shown in FIG. 5.
A threaded hole 79 and a supporting hole 78 are formed in a fixed plate 51 of an injection moulding machine so as to be arranged in series in the substantially horizontal direction. A supporting portion 72 of a support cylinder 62 is fitted into the supporting hole 78. A bearing portion 73 of the support cylinder 62 externally supports a roller member 64 rotatably through a bearing 63. A bolt 66 inserted into a cylindrical bore 65 of the support cylinder 62 is threadably engaged with the threaded hole 79 so as to press and secure the supporting portion 72 of the support cylinder 62 onto the fixed plate 5I by means of the bolt 66.
Incidentally, an axis of the bearing portion 73 is offset relative to an axis of the supporting portion 72 so as to enable an adjustment of a height position of the roller member 64.
A metal mould weight W acting on the roller member 64 during conveying of a metal mould 55 is received by a vertical resistive force V provided by a peripheral surface of the supporting hole 78. When a horizontal reaction force H acts from the fixed plate 51 to an end surface of the supporting portion 72 so as to cope with a moment (W.times.L) produced by the metal mould 55, the horizontal reaction force H is received by a tightening force F of the bolt 66. An allowable conveying load of the conveying roller 60 is so set that a value of the horizontal reaction force H becomes smaller than a maximum tightening force of the bolt 66.
In the conventional embodiment, since an arm length r of the horizontal reaction force H is small, the value of the horizontal reaction force H becomes much larger than the metal mould weight W. Therefore, the allowable conveying load of the conveying roller 60 is limited to a small value.
In order to solve the above-mentioned problem, it can be supposed that a diameter of the supporting portion 72 should be increased so as to enlongate the arm length r. In this case, however, since it becomes necessary to increase also a diameter of the supporting hole 78, it becomes difficult to drill the supporting hole 78 in an installation spot of the injection moulding machine. Therefore, it is troublesome to mount the conveying roller.